Addenda and Corrections to Plan for Defense against a Submarine Attack in Home Waters, Submitted by Admiral William S. Benson, Chief of Naval Operations

NAVY DEPARTMENT

Office of Naval Operations

Washington.

March 6, 1918.

The foregoing plan “Defense Against Submarine Attack in Home Waters”1 with the following alterations, modifications or changes is approved. Steps will be taken immediately to put into effect.

MODIFICATIONS AND CHANGES OR ALTERATIONS

OUTBOUND SHIPPING.

Par. 12 (c) – That the best practice is to have the coastwise shipping proceed by day hugging the shore and keeping within the five fathom curve or as near it as practicable. Also, since it is the policy of the Shipping Committee charged with such work, to allocate the smallest and least valuable ships to the coasting trade, it, as a matter of expediency, should be the policy to protect said shipping by the means within the capacity of the Naval Districts through which the coastwise shipping passes, rather than to attempt to divert guns from ships in the trans-Atlantic trade, or to allocate cruisers for theprotection of our coastwise trade, except in such cases where the districts could not afford protection, or the guns were readily available.

That if it were found expedient to route coastwise ships at night, that they should sail independently, being routed with due regard to the warnings received of the location of enemy submarines.

Par. 12 (g) change to read – That air scouts should patrol the convoys intended course out at least 50 fathoms curve and as far beyond as circumstances permit, or until darkness comes on.

Par. 12 (h) Omit the words “and by one or more escorting submarines for lookout.” It is the policy to use our submarines offensively against hostile submarines, and their movements are influenced by the movements of hostile submarines, not by the movements of our convoys.

Par. 12 (j) add at the end of paragraph – “and also of destroyers if advisable.”

Par. 12 (l) Omit entirely.

Par. 15 Last two lines, change to read – “shipping out of the Gulf of Mexico should be routed north or south of Cuba as circumstances existing at the time renders most expedient.”

Par. 16 – Hold to be not sound as the delay thus caused to shipping practically reduces its efficiency to a lower limit than the actual submarine sinkings could impose.

Par. 17 (n) – add the words “until such time as convoys can be established.”

Par. 27 (s) – That in view of the slight advantages to be derived as compared to the inordinate risk to shipping, the sub-surface mine will not be used offensively against hostile submarines – That it is legitimate to use it defensively, but that such use should be confined to the purpose of barring entrance and exit to our principal shipping ports and confined to the lowest limits compatible with a fair degree of safety. That even when a defensive mine field is laid, a clear and ample passage must be left for the transit of shipping, and this passage must under no circumstances be mined but be patrolled and protected by other means. That all mines upon being detached from their moorings must become innocuous. That the xxxx three places to be considered now as coming within the scope of defensive mining are New York – Capes of the Chesapeake – West Entrance to Long Island Sound.

Par. 29 (u) After the words Hampton Roads add – “But that owing to the great demand for mines abroad this step be not considered now.”

Par. 43 (kk) Read that a force consisting of at least one squadron of 20 airplanes will be needed at each station, Rockaway Inlet and Hampton Roads, and that this number should be made available as soon as practicable, not ot interfere with the European program.

Par. 45 – Add new paragraph (oo) – “Be prepared upon special order of the Navy Department to withdraw all light vessels on the Atlantic Coast, but this will be done only when the necessity is strongly apparent.”

Par. 45 – Add new paragraph (pp) – “Establish listening stations at the entrances to Chesapeake Bay, New York, and the East End of Long Island Sound. If these stations prove effective and are needed, to extend the system to other important localities.”